A somatic embryogenesis receptor kinase like
(SERKL) cDNA, designated PhSERKL, was isolated from date palm (Phoenix
Dactylifera L) using RACE PCR. PhSERKL protein shared all the
characteristic domains of the SERK family, including five leucine-rich
repeats, one proline-rich region motif, a transmembrane domain, and
kinase domains. Phylogenetic analyses using PHYLIP and Notung 2.7
programs suggest that the SERK proteins of some plant species resulted
from relatively ancient duplication events. We predict an ancestor
protein of monocots and dicots SERK using FASTML program. Somatic
embryogenic cultures of date palm were established following transfer of
callus cultures to medium containing 2, 4-dichlorophenoxyacetic acid.
The role of PhSERKL gene during establishment of somatic embryogenesis
in culture was investigated using quantitative real-time PCR. PhSERKL
gene was highly expressed during embryogenic competence acquisition and
globular embryo formation in culture. Overall, levels of expression of
PhSERKL gene were lower in nonembryogenic tissues and organs than in
embryogenic callus.

Phosphate (Pi) and its anhydrides constitute
major nodes in metabolism. Thus, plant performance depends directly on
Pi nutrition. Inadequate Pi availability in the rhizosphere is a common
challenge to plants, which activate metabolic and developmental
responses to maximize Pi usage and acquisition. The sensory mechanisms
that monitor environmental Pi and transmit the nutritional signal to
adjust root development have increasingly come into focus. Recent
transcriptomic analyses and genetic approaches have highlighted complex
antagonistic interactions between external Pi and Fe bioavailability and
have implicated the stem cell niche as a target of Pi sensing to
regulate root meristem activity.

Auxin regulates a host of plant developmental and physiological processes, including embryogenesis, vascular differentiation, organogenesis, tropic growth, and root and shoot architecture. Genetic and biochemical studies carried out over the past decade have revealed that much of this regulation involves the SCFTIR1/AFB-mediated proteolysis of the Aux/IAA family of transcriptional regulators. With the recent finding that the TRANSPORT INHIBITOR RESPONSE1 (TIR1)/AUXIN SIGNALING F-BOX (AFB) proteins also function as auxin receptors, a potentially complete, and surprisingly simple, signaling pathway from perception to transcriptional response is now before us. However, understanding how this seemingly simple pathway controls the myriad of specific auxin responses remains a daunting challenge, and compelling evidence exists for SCFTIR1/AFB-independent auxin signaling pathways.